Adjustable-Focus Glasses Counter Astronauts' Vision Problems

Space travel has damaging effects on vision. A new kind of glasses allows astronauts to shift the focus with the touch of a finger.

The view from space is amazing. But your vision in space—well, maybe not.

As long as humans have been going to space, scientists have been studying the weird physiological effects that weightlessness has on the human body. One clear change is in the eyes, and for a new study, eye experts worked with NASA to investigate longtime anecdotal complaints from astronauts that lengthy missions were damaging their eyesight—and to propose a clever techy solution.

First, the researchers found that 60 percent of astronauts on extended missions (such as trips to the International Space Station) experience vision trouble. Their problems usually arise in seeing things up close, which is no small problem when your job involves looking at an instrument panel. Even worse, the effect seems to stick around after the astronauts return to Earth. Something about space travel makes your eye go through a number of physical changes, including a rise in pressure around the optic nerve at the back of the eye. The changes resemble what you might see in a patient with some kind of mass in the brain, says Tom Mader, an eye surgeon and lead author of the study, which appeared in the journal Ophthalmology.

But in the space travelers' case, Mader thinks that this may have something to do with the fact that, in the absence of gravity, body fluids accumulate in the head. These excess body fluids cause astronauts to have a notably puffy-faced appearance, and also may build up the pressure inside their skulls. Fluid buildup could put pressure on the back of the eye and push the retina forward a tiny bit, he says, explaining the shift toward farsightedness that the astronauts are experiencing. Confirming this, however, won't be easy. Tests to keep track of pressure changes in the eye are difficult to do on a spacecraft. "Most of them are gravity-dependent," says Mader. "So we have to find something that will work in space."

NASA and eye experts are trying to find a way to correct for this space farsightedness. Since 1998, NASA has been sending astronauts up with "space anticipation glasses," one or more pairs with amped-up power that astronauts could switch through if their sight began to decline. Of course, switching glasses to alternately find your Tang and admire the scenery is no mean feat in zero-g, but there's a new solution heading into orbit.

The final space shuttle flights carried Superfocus glasses, which are now kept in stock on the ISS. They can be refocused with the turn of a dial, similar to a pair of binoculars. "These things are ideal for spaceflight," says study author Robert Gibson, an optometrist and consultant to NASA Flight Medicine.

Superfocus was created for Earth-dwellers over the age of 40 whose sight has begun to go downhill because of presbyopia, a condition that sets in as people age and their eyes' lenses lose their youthful flexibility, making it hard to adjust focus from far to near. And since the average astronaut age now is 48, many of them are already experiencing presbyopia, which the effects of space travel exacerbate.

Superfocus glasses have two components: a conventional lens toward the front, and near the eye, a flexible lens that bubbles out, changing the focus of the glasses. That solves the problem of having to either opt for bifocals, which leave part of the field of view perpetually blurry, or constantly switch back and forth between regular glasses and reading glasses.

If Superfocus does have one drawback, Gibson admits, it's that they are the most aesthetically refined specs out there. But even macho astronauts learn to look past their appearance. "You get those guys up there, and suddenly all they care about is that they can see," Gibson says.

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